Cellulose esters and process of making same



Patented Aug. 15, 1933 7 r r UNITED STATES PATENT OFFICE (JELnULosE Es'rEas AND rnoosss oF MAKING SAME Robert :Haller, ,Riehen, near Basel, and Andreas Roper-ti, Basel, Switzerland, assignors to firm H Society of Chemical Industry inBasle, Basel, Switzerland No Drawing. Application July 11,1931, Serial N-' 550,268, and in Switzerland February 28, 1930 a V Claims; (01. 260-401 v i V r he present invention, which is an improvedrying it in a vacuum; is washed with water and ment in or a modification of thatdescribed in dried. p 1 i o l specification Serial No. 514,307, filed February There are obtainedl lfi parts of .,an.ester hav- 7, 1931, relatesto the manufacture of new celing theoriginal fibrous structure, and contain- 5 lulose esters. It comprisesthe process of making approximately Zacetyl-groups per CsHioOs ing these esteraas well as the esters themselves. unit. It is insoluble in organic; solvents and is In the above cited specification it isshown Well suited for being worked up into soluble that while the esterification'of cellulose by means esters. of acetic anhydride proceeds with difficulty in i v E Z 5 ,10 thepresence of sodium acetate, the esterification r ramp l,

of cellulose by meansof aliphatic acid anhydrides 100 parts of viscoseartificial silk are immersed occurs very easily in the presence of potassium in'lilill) parts of a saturated aqueous solution of w salts ofweak acids. The reaction is particularly Sodium acetate. After an hour the silk is re- 7 smooth when the cellulose material, if desired mov d o the bath, dried and heated 1 l5 after previous swelling, isfirst impregnatedwith 110111 to bo ling in a o u o Of 250 Parts f the potassium salt, then dried and then treated acet c an yd de in 8 Parts Of Xylene, After with the anhydride of the aliphatic acid. cooling, the silk material is freed from adhering According to the present invention cellulose qu by centrifug and drying in a Vacu material can be esterifi d in hi0h degree and It is then Washed withwater and dried. There 20 easily by means of an aliphatic acid anhydride are obtained 130435 parts of an ester silk havin presence of a sodium salt of a weak a id, if, ing the properties similar to those described for 1 instead of adding the sodium salt to the esterithe p oduct Obtained W use Of potassium fying bath, the procedure recommended in the acetate in spec fi i Serial No. 514,307 of aforesaid specification is followed. Itis neces- 1 3 I sary to operate under conditions imparting a The esterification of cellulose artificial silk somewhat energetic reaction. Among othercondescribed in this example can obviously be conditions, the esterification advantageously producted at any suitable stage of the manufacceeds at a temperature not too low. ture. It may be applied even to the finished In the present invention the same Weak acids web or to dyed material, as has been explained H30 as named in application Serial No. 514,307 may in p c fic fl Serial V be used, such as acetic acid, carbonic acid, pro pionic acid, butyric acid, stearic acid, sulfurous Example 3 100 parts of wood pulp are soaked overnight acid, etc.

As acid anhydrides the same anhydrides are in mercerizing causticsoda solution (18 per cent.- also coming into consideration which are stated gth), then p e sed until the W i is three in application Serial No. 514,307, such as the times that of the cellulose material, disintegrated anhydride of acetic acid, propionic acid, butyric in the .W apparatus d eated acid, valeric acid, isovaleric acid, isobutyric acid, With a quantity o acetic c equivalent 0 the monochloracetic acid, etc. .alkali present, so as to neutralize the latter. 40 The following examples illustrate the i The material, if necessary with aid of a vacuum, tion, the parts being by weight: is dried in a drying chest, and acetylated as described in Example 1. The product is similar Example 1 to that obtained according to Example 1. parts of cotton are immersed for 1 hour What we claim is:- 45, in 1,000 parts of mercerizing caustic soda solu- A D o estelifying 0611111056 Whilst 100 tion, then removed from the bath, centrifuged maintaining its structure, which consists in imand thoroughly washed with water and again pregnating tirecellulose with a solution of a centrifuged; without drying the cotton is then sodium salt of a weak acid, drying and esteriimmersed in 1000 parts of a saturated aqueous Tying the material in the heat with an aliphatic 5 solution of sodium acetate. After 1 hour the acid anhydride in the absence of an acid catamaterial is removed from the liquor, centrifuged, lyst. dried and heated in acetic anhydride to boiling 2. A process for esterifying cellulose whilst. for 1 hour. The liquor is run off, while hot, and maintaining its structure, which consists'in imregenerated. The cellulose material, if desired pregnating the cellulose with asolution of a after the separation of the adherent liquid by sodium salt ofa weak aliphatic-acid, drying and esterifying the material in the heat with an aliphatic acid anhydride in the absence of an acid catalyst.

3. A process for esterifying textile materials consistingof cellulose whilst maintaining their structure, which consists in impregnating the material with a solution of a sodium salt of a weak aliphatic acid, drying and esterifyinggit in the heat with an aliphatic acid anhydride in the absence of an acid catalyst.

4. A process for esterifying textile materials consisting of cellulose whilst maintaining their structure, which consists in impregnating the swelled material with a solution of sodiumacetate, drying and esterifying it in the heat with acetic acid anhydride in the absence of an acid catalyst.

5. A process for 'esterifying regenerated cellulose whilst maintaining its structure, which consists in impregnating regenerated cellulose with a solution ofa sodium salt of a weak acid,-drying and esterifying the material in the heat with an aliphatic acid anhydride in the absence of an' acidcatalyst.

6. A process for esterifying regenerated cellulose whilst maintaining its structure, which consistsin impregnating regenerated cellulose with a solution of, sodium acetate, drying and esterifying the material in-the heat with acetic acid anhydride in the absence of an acid catalyst.

-'7. -A cellulose ester whichis' obtained by esterifying cellulose impregnated with a solution of a sodium salt of a weak acid with an aliphatic acid anhydride in the absence of an acid catalyst, the esterification being conducted in the heat, which product is insoluble in chloroform and acetone and constitutes an ester of nondegraded cellulose.

8. A cellulose ester which is obtained by elsterifying cellulose impregnated with a solution of a sodium salt of a weak aliphatic acid withan' aliphatic acid anhydride in the absence of an acid catlyst, the esterification being conducted'in the heat, which product is insoluble in chloroform and acetone and constitutes an ester of non-degraded cellulose.

9. A cellulose ester which is obtained by esteri- *fying regenerated cellulose impregnated with a solution of a sodium salt of a weak acid with an aliphatic acid anhydride in the absence of -an acid catalyst, the esterification being con- 

